Wireless device, distance estimation system, position estimation system, distance estimation method, position estimation method, distance-estimation-program recording medium, and position-estimation-program recording medium

Abstract

To precisely and rapidly estimate a distance and a relative positional relation between a plurality of wireless devices, a wireless device includes an RF-signal transmission means, an RF-signal reception means, a loopback path, and a control means. The control means includes a timing-pulse-signal transmission means, a timing-pulse-signal reception means, a delay-time reception means, and a distance estimation means. The loopback path loops back an RF signal transmitted from the RF-signal transmission means to the RF-signal reception means. When the wireless device transmits a first-timing-pulse signal and a second wireless device receives the signal, the second wireless device transmits a second-timing-pulse signal, triggered by the reception. The second wireless device further transmits a delay time between reception of the first-timing-pulse signal and transmission of the second-timing-pulse signal. The distance estimation means estimates a distance between the wireless devices, in accordance with the received first- and second-timing-pulse signals and the delay time.

What is claimed is: 
     
         1 . A wireless device comprising:
 RF-signal transmission unit for transmitting an RF signal;   RF-signal reception unit for receiving an RF signal;   an antenna transmitting and receiving the RF signal;   a loopback path looping back an RF signal transmitted by the RF-signal transmissions unit to the RF-signal reception unit; and   control unit for exchanging a signal between the RF-signal transmission unit and the RF-signal reception unit,   the control unit comprising:   timing-pulse-signal transmission unit for transmitting a timing pulse signal to the RF-signal transmission unit;   timing-pulse-signal reception unit for receiving a timing pulse signal from the RF-signal reception unit;   delay-time reception unit for receiving, from a second wireless device transmitting a second-timing-pulse signal triggered by reception of a first-timing-pulse signal transmitted by the local device as a first wireless device, a delay time between reception of the first-timing-pulse signal and transmission of the second-timing-pulse signal, respectively by the second wireless device; and   distance estimation unit for estimating a distance between the local device and the second wireless device, in accordance with the first-timing-pulse signal, the second-timing-pulse signal, and the delay time.   
     
     
         2 . The wireless device according to  claim 1 , further comprising
 identification-information assignment unit for assigning identification information, distinguishing the second-timing-pulse signal from the first-timing-pulse signal, to the second-timing-pulse signal.   
     
     
         3 . The wireless device according to  claim 2 , further comprising
 position estimation unit for estimating, in accordance with a reception time of a third-timing-pulse signal transmitted by a third wireless device different from the first and second wireless devices, delay time information transmitted by the third wireless device, and a distance estimation result of the distance estimation unit, a relative positional relation between the first wireless device, the second wireless device, and the third wireless device.   
     
     
         4 . A distance estimation system comprising a plurality of the wireless devices according to  claim 1 , wherein the plurality of the wireless devices mutually transmit and receive a timing pulse signal. 
     
     
         5 . A position estimation system comprising at least three of the wireless devices according to  claim 3 , wherein the at least three of the wireless devices mutually transmit and receive a timing pulse signal. 
     
     
         6 . A distance estimation method between wireless devices used in a wireless system composed of a plurality of wireless devices, the method comprising:
 transmitting, by a first wireless device, a first-timing-pulse signal;   receiving, by the first wireless device, the first-timing-pulse signal by loopback;   receiving, by a second wireless device different from the first wireless device, the first-timing-pulse signal;   transmitting, by the second wireless device, a second-timing-pulse signal, triggered by reception of the first-timing-pulse signal;   measuring, by the second wireless device, a delay time between reception of the first-timing-pulse signal and transmission of the second-timing-pulse signal;   transmitting, by the second wireless device, the delay time;   receiving, by the first wireless device, the second-timing-pulse signal and the delay time; and   estimating, by the first wireless device, a distance between the first wireless device and the second wireless device, in accordance with the first-timing-pulse signal transmission and reception times, the second-timing-pulse signal reception time, and the delay time.   
     
     
         7 . The distance estimation method according to  claim 6 , wherein
 identification information distinguishing the second-timing-pulse signal from the first-timing-pulse signal is assigned to the second-timing-pulse signal.   
     
     
         8 . A relative-position estimation method for a wireless device used in a wireless system composed of at least three wireless devices, the method comprising:
 transmitting, by a first wireless device, a first-timing-pulse signal;   receiving, by the first wireless device, the first-timing-pulse signal by loopback;   receiving, by a second wireless device different from the first wireless device, the first-timing-pulse signal;   transmitting, by the second wireless device, a second-timing-pulse signal, triggered by reception of the first-timing-pulse signal;   measuring, by the second wireless device, a first delay time between reception of the first-timing-pulse signal and transmission of the second-timing-pulse signal;   transmitting, by the second wireless device, the first delay time;   receiving, by a third wireless device different from the first wireless device and the second wireless device, the second-timing-pulse signal;   transmitting, by the third wireless device, a third-timing-pulse signal, triggered by reception of the second-timing-pulse signal;   measuring, by the third wireless device, a second delay time between reception of the second-timing-pulse signal and transmission of the third-timing-pulse signal;   transmitting, by the third wireless device, the second delay time;   receiving, by the first wireless device, the second-timing-pulse signal, the first delay time, the third-timing-pulse signal, and the second delay time; and   estimating, by the first wireless device, a relative positional relation between the first wireless device, the second wireless device, and the third wireless device, in accordance with the first-timing-pulse signal transmission and reception times, the second-timing-pulse signal reception time, the first delay time, the third-timing-pulse signal reception time, and the second delay time.   
     
     
         9 .- 10 . (canceled)